Plant

Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as flowering plants, conifers, ferns, mosses, and green algae, but do not include fungi and bacteria. The group is also called green plants. They obtain most of their energy from sunlight via photosynthesis using chlorophyll contained in chloroplasts, They obtain most of

their energy from sunlight via photosynthesis using chlorophyll contained in chloroplasts, which gives them their green color. Some plants are parasitic and may not produce normal amounts of chlorophyll to process photosynthesize. By 2010, there are estimated to be 300–315 thousand species of plants, of which the great majority are seed plants. The scientific study of plants is known as botany. A typical plant structure has two organ systems: the shoot system and the root system. The shoot system is above ground and includes the organs such as leaves, buds, stems, flowers (if the plant has any), and fruits (if the plant has any). The root system includes those parts of the plant below ground, such as the roots, tubers, and rhizomes.

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Pistil ►

Stigma

Style

Ovary

Anther

Filament

Stamen ►

Petal ►

Ovule ►

Sepal ►

Receptacle ►

Penducle ►

Fruit ►

Seed ►

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Flower

Flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (angiosperms). The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs. Flowers may facilitate outcrossing (fusion of sperm and eggs from different individuals in a population) or allow selfing (fusion of sperm and egg from the same flower). Some flowers produce diaspores without fertilization. Flowers contain sporangia and are the site where gametophytes develop. Flowers give rise to fruit and seeds. Many flowers have evolved to be attractive to animals, so as to cause them to be vectors for the transfer of pollen.

A stereotypical flower consists of four kinds of structures attached to the tip of a short stalk. Each of these kinds of parts is arranged in a whorl on the receptacle. A whorl is an arrangement of sepals, petals, leaves, or branches that radiate from a single point and surround or wrap around the stem. A whorl consists of at least three elements.

Most flowers have four whorls:

the calyx, a whorl of sepals

the corolla, a whorl of petals

the androecium, a whorl of stamens, including filaments and anther

the gynecium, a whorl of the female parts of a flower: the stigma, style and ovary

Mosses are bryophytes or non-vascular plants. They differ from "higher" plants by not having internal water-bearing vessels or veins, and no flowers and therefore no fruits, cones or seeds. They are small (typically 1–10 cm tall) and herbaceous and absorb water and nutrients through their leaves. Mosses have stems which may be simple or branched and upright or lax, simple leaves that often have midribs, roots (rhizoids) that anchor them to their substrate, and spore-bearing capsules on long stems. They harvest sunlight to create food through photosynthesis. Mosses do not absorb water or nutrients from their substrate through their roots, so while mosses often grow on trees, they are never parasitic on the tree.

Mosses have a gametophyte-dominant life cycle, i.e. its cells are haploid for most of its life cycle. Sporophytes (i.e. the diploid body) are short-lived and dependent on the gametophyte. This is in contrast to the pattern exhibited by most "higher" plants and by most animals.